Three-Dimensional Transesophageal Echocardiography in Degenerative Mitral Regurgitation Francesco F. Faletra, MD, Stefano Demertzis, MD, Prof, Giovanni Pedrazzini, MD, Prof, Romina Murzilli, MD, Elena Pasotti, MD, Stefano Muzzarelli, MD, Prof, Francesco Siclari, MD, Prof, and Tiziano Moccetti, MD, Prof, Lugano, Switzerland

The morphology of mitral valve (MV) prolapse and flail may be extremely variable, with dominant and secondary dynamic lesions. Any pathologic valve appears unique and different from any other. Three-dimensional (3D) transesophageal echocardiography is a powerful tool to evaluate the geometry, dynamics, and function of the MV apparatus and may be of enormous value in helping surgeons perform valve repair procedures. Indeed, in contrast to the surgical view, 3D transesophageal echocardiography can visualize MV prolapse and flail in motion and from different perspectives. The purpose of this special article is not to provide a comprehensive review of degenerative MV disease but rather to illustrate different types of mitral prolapse and flail as they appear from multiple 3D transesophageal echocardiographic perspectives using a series of clinical scenarios. Because in everyday practice, 3D transesophageal echocardiographic images of MV prolapse and flail are usually observed in motion, each scenario is accompanied by several videos. Finally, the authors provide for each scenario a brief description of the surgical techniques that are usually performed at their institution. (J Am Soc Echocardiogr 2015;-:---.) Keywords: 3D TEE, Mitral valve disease, Degenerative mitral regurgitation

Degenerative mitral valve (MV) disease with leaflet prolapse and flail and severe regurgitation is a progressive pathologic condition associated with increased risk for long-term complications, including heart failure and death.1-3 This condition is actually a spectrum of diseases ranging from prolapse or flail of an isolated segment in an otherwise normal sized valve (the so-called fibroelastic deficiency [FED]) to multisegment prolapse or flail of both leaflets due to an excess of myxomatous tissue and large annulus (Barlow disease). Intermediate stages of the disease are FED+, in which myxomatous changes occur in the prolapsing segment, and forme fruste, in which myxomatous changes affect more than one segment.4 It is widely accepted that MV repair represents the ‘‘state of the art’’ of surgical treatment.5 Compared with valve replacement, MV repair has undeniably lower perioperative mortality, improved survival, better preservation of postoperative left ventricular function, and lower long-term morbidity, regardless of technical complexity.6,7 Accordingly, MV repair is indicated in symptomatic patients or in those who, though asymptomatic, show initial findings of left ventricular dysfunction (class I), episodes of atrial fibrillation, or pulmonary hypertension (class IIa).8 Two-dimensional (2D) transthoracic echocardiography is considered the ‘‘first-line’’ imaging technique before MV repair, providing From Dipartimento di Cardiologia (F.F.F., G.P., R.M., E.P., S.M., T.M.) and Dipartimento di Cardiochirurgia (S.D., F.S.), Fondazione Cardiocentro Ticino, Lugano, Switzerland. Reprint requests: Francesco F. Faletra, MD, Fondazione Cardiocentro Ticino, Division of Cardiology, Via Tesserete 48, CH-6900 Lugano, Switzerland (E-mail: [email protected]). 0894-7317/$36.00 Copyright 2015 by the American Society of Echocardiography. http://dx.doi.org/10.1016/j.echo.2015.01.006

relevant data for the decision-making processes regarding the severity of regurgitation, the types of lesions, left and right ventricular function, and systolic pulmonary pressure. Two-dimensional transesophageal echocardiography (TEE) may complete the diagnosis, refining the type of lesion and providing useful information on the likelihood of repair. Currently, 2D TEE is considered an indispensable tool for cardiologists and anesthesiologists during MV repair.9 However, both these techniques have the disadvantage of being tomographic, and only a limited number of cross-sectional planes are useful and standardized. Moreover, the identification of mitral scallops in a given cross-sectional plane may vary according to the individual anatomy (e.g., a large P3 may unexpectedly be intersected by the ultrasound beam in a long-axis view), and misidentification of the lesion may also occur when the echocardiographic plane foreshortens the ventricle. Real-time three-dimensional (3D) TEE was launched in the diagnostic arena 1.15 mL) from those affected by fibroelastic degeneration valves (volume of prolapsed tissue < 1.15 mL). The morphology of degenerative MV disease is extremely variable, with dominant and secondary dynamic lesions, and any pathologic valve appears unique and different from any other. Accordingly, the purpose of this special article is not to provide a comprehensive review of degenerative MV disease but rather to illustrate different types of mitral prolapse and flail as they appear from multiple 3D transesophageal echocardiographic perspectives using a series of clinical ‘‘scenarios.’’ On the other hand, the surgical technique used for a given valve depends not only on the underlying anatomy but also on surgical experience and preference. Indeed, there is not one single type of correction for a given valve prolapse, and different surgeons tackle these valves differently according to their expertise, access modality (minithoracotomy vs sternotomy) and their ‘‘surgical school.’’ In this article, we provide for each scenario a brief description of the surgical techniques that that are usually performed at our institution. Finally, in everyday practice, 3D transesophageal echocardiographic images of prolapse and flail are usually observed in motion; accordingly, each scenario is accompanied by several videos. The multipanel figures are still images derived from the corresponding videos chosen to indicate particular anatomic features or to emphasize specific 3D perspectives. Abbreviations

THREE-DIMENSIONAL TRANSESOPHAGEAL ECHOCARDIOGRAPHIC MITRAL VALVE IMAGING ACQUISITION The ideal imaging technique for visualizing the ‘‘dynamic’’ morphology of MV prolapse and flail requires high spatial resolution to identify fine morphologic details of the valve and high temporal resolution, which makes leaflet motion look ‘‘fluid’’ and natural, allowing an accurate frame-by-frame analysis of leaflet motion without large temporal gaps between frames. The temporal resolution of 3D TEE depends on the number of volumes scanned per second (volume rate). Because there is an inverse relationship between temporal resolution and the width of the pyramidal data set, the operator can change the volume rate by acting both on the volume width and depth: decreasing the volume width automatically increases volume rate.

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The spatial resolution in the beam direction (i.e., the axial resolution) depends exclusively on the pulse length; it is typically in the range of 0.8 to 1.0 mm and is unrelated to the volume rate or to the size (width and depth) of the pyramidal data set. The spatial resolution lateral to the beam direction (i.e., the lateral and elevation resolution) depends primarily on beam width and geometry. However, in a narrow sector, the spaces between lines are reduced (i.e., the line density is increased), and consequently, both temporal and spatial resolution is improved. Line density can also be electronically changed independently. In general, it can be stated that the narrower the pyramidal data set, the higher the spatial (both lateral and elevation) and temporal resolution. There are three main options of acquiring a volumetric data set of the MV: ‘‘zoom’’ mode, wide-angle single-beat, and full volume multiple-beat. Table 1 summarizes limitations and advantages of each modality. Briefly, the zoom mode is a real-time modality and consequently does not suffer from artifacts due to arrhythmias or patient or probe movement. When zoom mode is activated, two orthogonal 2D preview images show the ‘‘truncated’’ pyramid. The operator can then move this pyramid over the region of interest and adjust its size accordingly. Minimizing the sector width and length is important for increasing temporal resolution. Thus, although this modality is particularly useful for small structures such as the aorta or the left atrial appendage, it may be less suitable for a large degenerative MV. Indeed, to include the entire valve from lateral to medial commissure, the truncated pyramid must be wide enough that a reduction in temporal resolution up to 10 to 12 volumes/sec is inevitable. Moreover, increasing the volume width results in decreases in line density and, consequently, spatial (lateral) resolution. The full-volume multiple-beat modality uses electrocardiographic gating to capture a large volumetric data set by acquiring narrow subvolumes over two to seven sequential cardiac cycles. Being a summation of these subvolumes, this modality, despite the large sector (90  90 ), maintains the same high spatial resolution and provides a view of the whole MV with excellent image quality. Moreover, the high temporal resolution (up to 56 Hz) allows frame-by-frame analysis of leaflet motion, making this acquisition a formidable modality for accurately defining even small morphologic (and functional) valve abnormalities. Finally the same modality may display 3D color Doppler with an acceptable volume rate (up to 25–30 volumes/ sec), though with a narrower sector. However, this modality is not ‘‘real time’’ (the last sector is acquired four to six beats after the first), and it may suffer from ‘‘stitching’’ artifacts caused by incorrect juxtaposition of subvolumes due to respiration, irregular heart rhythm, or any transducer or patient movement. Thus, to avoid or minimize stitching artifacts, the patient must be in sinus rhythm and must stay very still, suspending breathing for a few seconds, while the operator must avoid moving the probe during the acquisition. These conditions might not always occur in patients with severe mitral regurgitation (MR). However, if correctly acquired, full volume is the ideal modality for imaging the MV. Accordingly, the videos presented in this review have been obtained with full-volume acquisition. Videos 1–3 (available at www.onlinejase.com) show the differences among the three acquisition modalities in the same MV P2 prolapse. In zoom mode (Video 1), spatial resolution is preserved, and small secondary lesions can be seen medially to the main lesion (in the P3 area). However, the width sector used to embrace the entire valve results in a temporal resolution as low as 9 Hz; Video 2 shows the same valve acquired with a wide-angle single beat. Spatial resolution appears slightly worse in comparison with zoom mode (the edges of the secondary lesions

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Table 1 Modalities of acquisition of the MV Type of acquisition

Display

Advantages

Limitations

Zoom mode

Magnified, truncated pyramidal data set of variable size

Real time, no artifacts due to arrhythmias or patient/probe movements

Spatial and temporal resolution depending of the size of the truncated pyramidal data set Enlarging the region of interest to include the entire MV may result in a decreased temporal (volume rate up to 10–12 volumes/sec) and spatial (same number of ultrasound lines must cover a wider sector) resolution

Wide-angle single-beat mode

Large sector (up to 90  90 )

Real time, no artifacts due to arrhythmias or patient/probe movements

Relatively lower temporal (10–12 volumes/sec) and spatial resolution

Full-volume multiple-beat mode

Sectors 90  90

Optimal spatial and temporal resolution (volume rate up to 56 volumes/sec)

No real time Stitching artifacts

appear less defined), whereas the temporal resolution is slightly increased (10 Hz). Finally, Video 3 shows the same valve acquired with the full-volume multiple-beat modality. The main difference with the other two acquisitions is the temporal resolution (up to 40 Hz), which makes the motion looks fluid and natural. Resolution is also slightly increased, defining more clearly the prolapse and secondary lesions.

Scenario 1: Isolated Flail of the Central Segment of the Posterior Leaflet (P2) This valve anomaly is usually caused by FED. Deficiencies of collagen, elastin, and proteoglycans with an altered elastic fibril architecture result in thin and fragile leaflet tissue with a translucent (pellucid) appearance.17 However, over time, the proliferation of pathologic tissue may occur in prolapsing segments, which may become thick and redundant. Video 4 (available at www.onlinejase.com) shows a ‘‘classic’’ isolated flail of the central segment of the posterior leaflet (P2) from an overhead perspective. This perspective clearly shows the extension of the prolapsing tissue along its attachment to the annulus. This extension can be measured directly on the 3D image (see Figure 1F) and has relevance for the type of surgical technique adopted. Videos 5 and 6 (available at www.onlinejase.com) show the same flail from angled lateral and angled medial perspectives, respectively. Being nearly tangential to the mitral plane, these views clearly display the degree of protrusion into the left atrium. Finally, from all perspectives, the excess tissue of the prolapsing segment is evident (see subtle irregular corrugations on its atrial surface), while the remaining valve tissue of both anterior and posterior leaflets appears normal. According to the definition proposed from Adams et al.,4 this morphology can be described as FED+. Surgical Technique. Isolated prolapse or flail of P2 is the most frequent dysfunction of degenerative MR and has been the first mitral abnormality to be repaired.18 The surgical technique may vary according to the extension and height of the prolapsing tissue.19,20 In limited posterior leaflet prolapse (less than one-third of the total free edge for the posterior leaflet), the valve can be repaired with a simple triangular resection of the prolapsing tissue. Leaflet continuity

is then restored with a suture. Triangular resection is quicker and easier to perform and is particularly valuable in the setting of minimally invasive approaches. In extensive posterior leaflet prolapse more than one-third of the total free edge for the posterior leaflet, a quadrangular resection is preferred. A plication of the annulus is used to approximate the remaining leaflet tissue. Leaflet continuity is then reestablished with a suture. When the height of remaining tissue is excessive (i.e., >20 mm), a limited resection at the base of the leaflets is carried out to restore optimal height (usually 20 mm) a sliding leaflet plasty is performed. The segments adjacent to the removed tissue are disconnected from the annulus medially and laterally to the resected area over a distance equal to one-half of the length of the gap. ‘‘Compression sutures’’ or plication is used to reduce the size of the annulus. Each segment is then pulled toward the gap until it covers half the gap and is reattached to the annulus by consecutive stitches. The repair is always completed with the addition of an annuloplasty with a semirigid full ring.21 Table 2 summarizes the different surgical techniques used for repairing P2 prolapse. Figure 2 is a schematic drawing showing the principal steps of the quadrangular resection and sliding plasty. Scenario 2: Prolapse of Both Leaflets Videos 7–10 (available at www.onlinejase.com) show a large prolapse mostly affecting the central and medial segments of both posterior and anterior leaflets, due to excessive valve tissue and elongated chordae tendineae. Although the diseased tissue does not embrace the entire valve (indeed, P1 and A1 appear normal), these pathologic features can most likely be described as a forme fruste of Barlow disease. Video 7 shows the valve from a slightly modified overhead perspective, while Videos 8 and 9 show the same valve from angled lateral and angled medial perspectives. The angled perspectives enhance the visualization of the commissures. Video 10 is a full-volume acquisition from an angled lateral view of 3D color Doppler revealing that the main regurgitant jet originates from the cleft between P2 and P1. Figure 3 shows a collage of still-frame images derived from the aforementioned videos.

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Figure 1 Sequential still-frame images derived from Video 1 showing a flail of the central segment of the posterior leaflet (P2) from mid-diastole (A) to mid-systole (H) from an overhead perspective. The dotted line in (F) marks the extension of the prolapsing tissue at its annular attachment. The arrow points to the ruptured chordae. Surgical Technique. Large prolapses with redundant tissue may be repaired by the implantation of artificial neochordae and an annuloplasty with a flexible complete ring. The advent of artificial chordae has indeed greatly enhanced the armamentarium of techniques available to repair degenerative MR and is now an essential component for the conservative treatment of even the most complex MV disease. Numerous techniques of artificial neochordae implantation have been developed, with particular attention focused on defining their correct lengths. It is beyond the scope of this review to provide a detailed description of these techniques. Herein we describe some basic concepts. The general idea of implanting several neochordae is based on the ‘‘respect rather than resect’’ approach.22 Artificial chordae of polytetrafluoroethylene (almost indistinguishable from native chordae) are implanted between the fibrous tip of papillary muscles and the margin of prolapsing segment. The aim is to create a large surface of cooptation while preserving leaflet tissue and maintaining normal leaflet motion. A critical point of this surgical technique is determining the appropriate lengths of the neochordae. A neochord that is too short will, in fact, result in restricted leaflet movement. A neochord that is too long will be ineffective in abolishing leaflet prolapse. Although various techniques have been described to determine the optimal length of the artificial chordae, this has remained somewhat problematic, and an accurate chordal height adjustment often remains intuitive and based on personal experience. Usually after ring placement, the chords (already fixed to papillary muscles) are woven into leaflets and individually ‘‘adjusted’’ to the most effective length.23 Recently Huang et al.24 described a 3D transesophageal echocardiographic method that can ‘‘predict’’ the length of artificial chordae preoperatively with the heart beating rather than arrested. The authors measured the distance from the expected coaptation line of the prolapsing leaflet to the nearest tip of papillary muscle in systole using quantitative software. This distance was then considered the reference length for the neochordae. The predicted length was almost identical to the length of implanted neochordae. When several neochordae are attached both medial and laterally, it is important to orient the neochordae according their original

anatomic distribution (i.e., neochordae to the medial leaflets are anchored to the posteromedial papillary muscle and neochordae to the lateral leaflets to the anterolateral papillary muscle), thus reproducing as closely as possible the native chordal arrangement. Figure 4 shows a schematic drawing and two intraoperative photos showing the main step of neochord implantation.

Scenario 3: A2 Prolapse Video 11 (available at www.onlinejase.com) shows an isolated prolapse of A2 caused by elongated chordae tendineae from an overhead perspective and Videos 12 and 13 (available at www. onlinejase.com) from angled lateral and angled medial perspectives, respectively. From any perspective, the extension of prolapsing tissue appears limited to the central part of A2 (less than one-quarter of the total length of the free edge of the leaflet). Currently, these measurements can be taken directly on the 3D image (see Figure 5A and 5E). The regurgitant orifice is positioned medially to the protruding tissue. In fact, the orifice is well visible from a lateral perspective (Video 12) but not from a medial perspective (Video 13). Despite the small extension of the prolapsing tissue, the regurgitant orifice is large enough to cause a severe regurgitation (Video 14). Figure 5 shows a collage of still-frame images obtained from the aforementioned videos. Correction of the anterior leaflet because of elongated or ruptured chordae is technically more challenging than is reconstruction of the posterior leaflet. Because of anatomic constraints, extensive resection of anterior leaflet tissue is in fact not feasible. Thus, MV repair strategies are focused on preserving rather than resecting significant areas of anterior tissue. The choice of the appropriate technique mainly depends on the extent of the prolapse. Surgical Technique. Very limited anterior leaflet prolapse or flail (i.e., less than one quarter of the total length of the free edge of the leaflet), such as that shown in this scenario, can be treated with a small triangular resection of prolapsed tissue; the triangular resection must

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Table 2 Techniques for repair of P2 prolapse and flail Type of prolapse

Morphometric characteristics

Surgical technique

Limited P2 prolapse

Prolapse less than one-third of the total free edge of the posterior leaflet

Triangular resection, leaflet continuity restored either with interrupted stitches or with a continuous, blocked suture; ring annuloplasty

Extensive P2 prolapse

Prolapse more than one-third of the total free edge of the posterior leaflet; height of remaining tissue < 20 mm

Quadrangular resection, plication of the annulus (used to approximate the remaining leaflet tissue); leaflet continuity reestablished either with interrupted stitches or with a continuous, blocked suture; plication of the annulus and ring annuloplasty

Extensive P2 prolapse

Prolapse more than one-third of the total free edge of the posterior leaflet; height of remaining tissue >20 mm

Quadrangular resection, limited resection at the base of the leaflets to restore optimal height (20 mm

Sliding leaflet plasty: the segments adjacent to the removed tissue are disconnected from the annulus medially and laterally to the resected area over a distance equal to one-half the length of the gap; each segment is pulled toward the gap and reattached to the annulus by consecutive stitches; plication of the annulus and ring annuloplasty

be limited to the rough zone so as not to distort the geometry of the leaflet. An alternative surgical technique is ‘‘secondary chordae transfer.’’ A secondary chorda inserted on the rough zone of the same leaflet is detached near its origin on the body of the anterior leaflet and reattached to the free margin of prolapsing area. This technique is recommended when the distance between the native chordal insertion and the free margin is >5 mm. Extensive anterior leaflet prolapse or flail (i.e., prolapsing tissue more than one-quarter of the leaflet surface area) should be treated with alternative techniques, such as implanting several neochordae (as previously described) or chordal transfer from the posterior to the anterior leaflet. This latter technique consists of transferring normal chordae and a strip of variable height of posterior leaflet (generally from the middle scallop) to the prolapsing or flail region of the anterior leaflet. The posterior leaflet is reconstructed as in quadrangular resection (Table 3). Scenario 4: P2 Flail and A2 Prolapse with Posterior Annular Calcifications In 2D echocardiography, calcium is recognized because of its brighter appearance in comparison with soft tissue. In 3D echocardiography, the variable shade of beige or blue color (or degrees of gray) provides the perception of the depth of the structures in relation to the observer rather than distinguishing calcifications from soft tissue. In 3D echocardiography, therefore, mitral annular calcifications can be recognized only because they protrude above the annulus and are relatively fixed. Video 15 (available at www.onlinejase.com) shows the MV from an overhead perspective. From this point of view, two main lesions can be recognized: a flail with ruptured chordae tendineae in the posterior leaflets (P2) and a small central prolapse of the anterior leaflet due to elongated chordae (A2). The two lesions are not completely facing each other, given that the A2 prolapse is situated

medial to the P2 flail. The P2 flail has a ‘‘limited’’ extension (see Figure 6A). Moreover, it is also evident from this view that the posterior annulus in correspondence to the P2 appears stiff, with three protuberances. These protuberances correspond to an extensive annular calcification that partially intrudes into the leaflet tissue. Videos 16 and 17 (available at www.onlinejase.com) show the same valve from angled lateral and angled medial perspectives, respectively. Both perspectives enhance the visualization of the three calcified blocks encroaching into the base of the P2. Video 18 (available at www.onlinejase.com) shows the valve from an anterior perspective. From this view, the anatomic regurgitant orifice is clearly visible and the three calcific prominences are seen ‘‘en face.’’ Figure 6 shows a collage of still-frame images obtained from the aforementioned videos. Annular calcification is often associated with degenerative MR. Calcifications are usually confined to the posterior annulus but in some patients may extend to the anterior annulus, invade leaflets, or, more rarely, also invade ventricular myocardium and papillary muscles. Surgical Technique. MV repair of the posterior leaflet in patients with calcified MV annulus can be a challenge for the surgeon. Although quadrangular resection and ring annuloplasty after complete ‘‘en bloc’’ decalcification of the posterior MV annulus has been described,25 this technique remains technically challenging and may be complicated by thromboembolic events and atrioventricular disassociation.26 In a case shown in this scenario, calcifications intrude deeply into the posterior leaflet, making annular decalcification difficult. On the other hand, the extension of the prolapsing tissue of P2 is limited and can therefore be repaired with a simple triangular resection. Because the resection usually does not involve the annulus, the annular calcifications do not interfere with the repair and may be left ‘‘in situ.’’ The prolapse of A2 is a second abnormality that may be repaired with the insertion of neochordae, as previously described.

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Figure 2 A schematic drawing showing the main steps of quadrangular resection of the posterior leaflet prolapse and sliding plasty. (A) Dotted lines indicate the lines of resection and sliding plasty; (B) segments adjacent to the removed tissue are disconnected from the annulus (arrows); (C) a ‘‘compression suture’’ reduces the size of the annulus (arrows); (D) leaflet continuity is reestablished with a suture (arrow).

Figure 3 Still-frame images obtained from Videos 4–6 in mid-diastole (A–D) and mid-systole (E–H). The valve is shown from a slightly modified overhead perspective (A,E) and from medial (B,F) and lateral (C,D) perspectives. The angled perspectives are an optimal point of view for visualizing commissures. The arrows in (G) point to the borders between prolapsing and nonprolapsing (A1 and P1) tissue. (D,H) Still-frame images of 3D color Doppler clearly revealing that the regurgitant jet arises from this area (arrows). Ao, Aorta; Cs, coronary sinus.

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Figure 4 Composite image including (A) a schematic drawing illustrating the suture placed from the head of the papillary muscle (PM; red arrow) to the free edge of the mitral leaflet (ML; black arrow) and (B,C) two intraoperative photos illustrating two moments of the valve repair with a neochord. (B) The suture is tied with several knots (white arrow) so that it does not interfere with the coaptation line. (C) The result with a ring annuloplasty.

Table 3 Techniques for repair of A2 prolapse and flail Type of prolapse

Morphometric characteristics

Surgical techniques

Limited A2 prolapse

Prolapse tissue less than one-quarter of the total free edge of the anterior leaflet

Triangular resection with resection limited to the rough zone

Limited A2 prolapse

Distance between the ‘‘normal’’ native chordae inserted on the rough zone of the same leaflet and the free margin of prolapsing tissue >5 mm

Secondary chordae inserted on the rough zone of the same leaflet are detached near their origin on the body of the anterior leaflet and reattached to the free margin of the prolapsing area Alternative technique: implantation of a neochord

Extensive A2

Prolapse tissue more than one-quarter of the total free edge of the anterior leaflet

(1) Implantation of a neochord to the free margin of A2 (2) Alternative technique: transferring a strip of variable height of the posterior leaflet with its chordae to the prolapsing or flail region of the anterior leaflet; the posterior leaflet is reconstructed as in triangular or quadrangular resection (chordal transfer)

Scenario 5: Multisegment Single-Leaflet Prolapse Video 19 (available at www.onlinejase.com) shows the MV from an overhead perspective. Here, it is not completely clear which segments of the posterior leaflet significantly prolapse into the left atrium. Indeed, from an overhead perspective, leaflet tissue protruding into the left atrium can be distinguished because the algorithm assigns shades of beige brighter than the surrounding nonprolapsing segments; however, detecting small prolapses from this perspective may be challenging because differences in shades between prolapsing and nonprolapsing tissue may be rather indistinct. Conversely, an angled lateral perspective (Video 20; available at www.onlinejase.com) enhancing the edges of the prolapsing tissues allows a clearer image of the large central prolapse (P2) and of the smaller lateral (P1) and medial (P3) prolapses. Finally, Video 21 (available at www.onlinejase.com) shows an anterior perspective confirming the prolapse of the entire posterior leaflet. Moreover, the same perspective displays a large regurgitant orifice. Figure 7 shows a collage of still-frame images obtained from the aforementioned

videos. The extensive prolapse shown in this scenario is probably due to myxomatous infiltration of the posterior leaflet and the elongation of chordae. Surgical Technique. Most of the surgical techniques described above (i.e., quadrangular resection, insertion of neochordae, and ring annuloplasty) can be effectively applied to this valve. Scenario 6: Barlow Disease The 3D appearance of the valve is that of the classic Barlow disease. Most Barlow valves have, by definition, large annuli and thick and spongy leaflets (due to excessive myxomatous proliferation), which destroy the three-layer leaflets’ architecture and cause elongated or ruptured chordae.17 From an overhead perspective (Video 22; available at www.onlinejase.com), the central part of the posterior segment (P2) appears to prolapse into the left atrium more than the other segments. From this perspective, the annular circumference can be easily measured directly on the 3D image (see Figure 8A).

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Figure 5 Mid-diastolic (A–D) and mid-systolic (E–H) still-frame images taken from the corresponding videos. (A,E) The valve is shown from an overhead perspective; from this perspective, the extension of prolapsing tissue and the length of the free margin of the anterior leaflet can be measured directly on 3D images (dotted double-headed arrow lines). The valve is shown from medial (B,F) and lateral (C,D) perspectives. (E,F) The arrows point to the prolapsing bilobulated segment, while the asterisk marks the regurgitant orifice, which appears located medially to the prolapsing tissue. (D) A still-frame image of 3D color Doppler in mid-diastole with laminar flow (blue color) crossing the valve. (H) The same valve in mid-systole with severe MR. The white arrow points to the convergence area, while the red arrow indicates the regurgitant jet. Ao, Aorta; CS, coronary sinus; LAA, left atrial appendage.

Video 23 (available at www.onlinejase.com) shows the valve from an angled lateral view. This perspective confirms the large prolapse of P2 and heightens the protrusion of P1 and A1. Conversely, Video 24 (available at www.onlinejase.com) shows the valve from an angledmedial perspective, which highlights the prolapse of A3 and P3. Finally, Video 25 (available at www.onlinejase.com) shows the valve from an anterior perspective: the P2 prolapse overrides the other prolapsing segments, forming the regurgitant orifice. Figure 8 shows a collage of still-frame images obtained from aforementioned videos. Surgical Technique. Barlow disease is characterized by a severe billowing of both leaflets due to significant excess tissue. The excess leaflet tissue poses a specific challenge during MV repair because it can predispose the development of systolic anterior motion of the valve. This complication may occur either because, after resection, the residual leaflet tissue is left so high that it displaces the anterior leaflet toward the left ventricular outflow tract or because the annuloplasty ring is too small to force excess tissue into the left ventricular outflow tract. The former cause may be resolved with a sliding technique (see scenario 1), while the latter cause requires a large annuloplasty ring that respects the excess anterior leaflet tissue.27 Therefore surgical repair of this valve requires the following surgical actions: (1) quadrangular resection of P2 followed by a sliding plasty of the remaining lateral and medial scallops, (2) implantation of neochordae, and (3) large-ring annuloplasty. The double-orifice technique (Alfieri’s stich) merits mention because it has drastically simplified the repair of Barlow disease.28 This technique approximates the posterior leaflet with the counterpart of the anterior leaflet by a properly placed edge-to-edge stitch that encompasses a large amount of leaflet tissue. In combination with a very large complete ring, Alfieri’s stich can effectively lead to

marked shortening of the height of both leaflets and a lowering of the coaptation point to within the left ventricle. Because of its technical simplicity and reproducibility, this technique can be easily applied when a minimally invasive approach is performed.29

MITRAL ANNULOPLASTY All the above-described surgical techniques require mitral annuloplasty. Annuloplasty is in fact the most commonly performed procedure, either as a stand-alone repair (as in functional MR) or in combination with leaflet or subvalvular repair. Adding a ring after leaflet and/or subvalvular valve reconstruction improves leaflet coaptation, reduces the stress on the leaflets and on the suture lines, and reshapes annular stabilizing annular dimensions over time; in other words, it increases the durability of valve repair. Two steps of the procedure deserve to be mentioned: ring selection and ring sizing. Today a variety of annuloplasty rings (flexible, semirigid, or rigid; incomplete or complete; planar or saddle shaped; adjustable or nonadjustable) are available. Flexible or semirigid rings, either complete or partial, are usually used to treat degenerative MR. Moreover, a new generation of rings have been designed to treat specific etiologies. In particular, in Barlow disease, a new ring (Myxo ETlogix; Edwards Lifesciences, Irvine, CA) has been designed specifically to accommodate the excess tissue and to move the coaptation point away from the septum, thus reducing the risk for systolic anterior motion and the need for complex resection.30 Finally, the size is chosen according to three measures: the intertrigonal distance, the intercommissural distance, and the extension of anterior leaflet surface.

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Figure 6 Still-frame images acquired from the corresponding videos in mid-systole (A–D) and in mid-diastole (E–H). (A,E) The valve is shown from an overhead perspective. The dotted line in (A) marks the extension of prolapsing tissue. The valve is shown from angled medial (B,F) and lateral (C,D) perspectives. (D,H) The valve is shown from an anterior perspective. The flail of the posterior leaflet (P2) and the prolapse of the anterior leaflet (A2) are well visible from any perspective. The arrow points to a ruptured chorda. From the overhead perspective (A), it is clear that the two lesions are not facing each other. An extensive calcification (CA) is placed on the posterior annulus around to the flail tissue and can be seen from any perspective (asterisks). (D) The red arrow points to the anatomic regurgitant orifice.

Figure 7 Still-frame images acquired from the corresponding videos in end-diastole (A–D) and in mid-systole (E–H). (A,E) The valve is shown from an overhead perspective and from medial (B,F) and lateral (C,D) perspectives. (D,H) The valve is shown from an anterior perspective. Although from an overhead perspective, it is not entirely obvious which segments are prolapsing into the left atrium, from angled perspectives (F,G), the prolapse of central, lateral, and medial prolapses is unequivocally clear. (H) The multisegment prolapse of the posterior leaflet and the large regurgitant orifice (asterisk) are confirmed. Ao, Aorta.

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Figure 8 (A) A still-frame image from the overhead perspective that emphasizes the deep protrusion of the P2 segment. The dotted circle marks the annular circumference that can be measured as well as the diameters directly on the 3D image. (B) A still-frame image derived from a lateral perspective. From this perspective, the lateral segments of the leaflets are seen ‘‘en face,’’ and therefore their protrusions are easily detected. Conversely, A3 and P3 prolapse is best detected from a medial perspective (C), as shown in Video 20. (D) An anterior perspective. The still-frame image emphasizes the overriding of the P2 segment (arrow). Ao, Aorta; LAA, left atrial appendage.

TRANSCATHETER TECHNOLOGIES FOR MV REPAIR In MV prolapse and flail, surgical repair remains the preferred treatment. However, in a significant proportion of patients considered at high risk (i.e., elderly persons or patients with severe comorbidities or severe left ventricular dysfunction), surgery may be denied. In the past decade, several transcatheter procedures have emerged for these high-risk or inoperable patients. Some are now well established and are part of interventional cardiologists’ armamentarium (such as percutaneous edge-to-edge valve repair). Others, such as percutaneous chordal repair and different percutaneous annuloplasty devices, are at different stages of development. Percutaneous chordal implantation is technically very challenging and is currently under development.31 The use of different devices implanted into the coronary sinus (with the aim of reducing the posterior portion of the mitral annulus and improving leaflet coaptation) has been proposed mainly for functional rather than degenerative MV regurgitation. This procedure has the advantage of being relatively simple (it needs only transvenous femoral access and fluoroscopic guidance). However, often the coronary sinus is not on the same plane as the mitral annulus,32 and the circumflex coronary artery or its branches may lie between the coronary sinus and the posterior mitral annulus.32

So, despite the simplicity of the procedure and apparent benefits suggested by early data,33 the procedure is currently under critical revision.34 Although for the aforementioned procedures, data regarding the usefulness of 3D TEE are scarce or absent, for percutaneous edgeto-edge valve repair, a careful preprocedural evaluation of mitral geometry, dynamics, and function as well as the site and size of regurgitant orifice is as critical as it is for surgical valve repair. With increasing expertise of interventional cardiologists, previous anatomic suitability criteria based on morphologic aspects of the valve (flail gap distance between A2 and P2 < 10 mm, central regurgitant orifice or flail leaflet width > 15 mm)35 are no longer considered absolute contraindications. Many patients, otherwise inoperable, can currently be successfully treated with one or more clips despite unfavorable anatomy (i.e., leaflet gap > 10 mm, multiple-scallop or commissural prolapse). Even more relevant is the role of TEE during the procedure. Because soft tissue such as mitral leaflets is invisible on fluoroscopy, a percutaneous edge-to-edge repair simply cannot be performed without echocardiographic guidance. Silvestry et al.36 proposed well-standardized 2D transesophageal echocardiographic planes for each step of the procedure. A few years ago, Perk et al.37 suggested, for the first time, the use of 3D TEE, predicting its pivotal role. Today, 3D TEE has been used

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alongside 2D TEE in many steps of the procedure,38 and it is frequently requested by interventional cardiologists.

CONCLUSIONS We have presented different morphologic features of degenerative MR and surgical therapy in the form of clinical scenarios. We have chosen these six scenarios using the following criteria:(1) a variety of types of degenerative MR, requiring different surgical techniques, so that the most common surgical techniques could be illustrated, and (2) complex pathologic features, so that the utility of the 3D transesophageal echocardiographic ‘‘segment-oriented approach’’ method and the 3D ‘‘angled perspectives’’ could be emphasized. We have also highlighted the importance of acquiring 3D data sets in full-volume mode. This type of acquisition allows imaging fine details of the leaflet anatomy (high spatial resolution) while displaying leaflet motion as ‘‘fluid and natural’’ (high temporal resolution). We are also aware that the six scenarios illustrated in this review do not cover completely the large spectrum of pathologic features of degenerative MR and that surgical descriptions are certainly incomplete, reflecting the ‘‘modus operandi’’ of our surgical team. Finally, we must say that although 3D TEE, when performed skillfully, can provide exquisite views of the MV apparatus in a dynamic manner, and although these views make sense and seem to correspond to surgical anatomy, there is no ‘‘gold standard’’ to judge the accuracy of 3D transesophageal echocardiographic images.

SUPPLEMENTARY DATA Supplementary data related to this article can be found at http://dx. doi.org/10.1016/j.echo.2015.01.006.

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35. Feldman T, Wasserman HS, Herrmann HC, Gray W, Block PC, Whitlow P, et al. EVEREST II investigator. Percutaneous mitral valve repair using the edge-to-edge technique: six-month results of the EVEREST Phase I Clinical Trial. J Am Coll Cardiol 2005;46:2134-40. 36. Silvestry FE, Rodriguez LL, Herrmann HC, Rohatgi S, Weiss SJ, Stewart WJ, et al. Echocardiographic guidance and assessment of percutaneous repair for mitral regurgitation with the Evalve MitraClip: lessons learned from EVEREST. J Am Soc Echocardiogr 2007;20:1131-40. 37. Perk G, Lang RM, Garcia-Fernandez MA, Lodato J, Sugeng L, Lopez J, et al. Use of real time three-dimensional transesophageal echocardiography in intracardiac catheter based intervention. J Am Soc Echocardiogr 2009; 22:865-82. 38. Faletra FF, Pedrazzini G, Pasotti E, Petrova I, Drasutiene A, De Quarti MC, et al. Role of real-time three dimensional transoesophageal echocardiography as guidance imaging modality during catheter-based edge-to-edge mitral valve repair. Heart 2013;99:1204-15.